Cavity Count: Choosing the Mould Size for a Real Volume

Cavities Trade Cost Against Capacity

Each cavity adds tool cost and adds output linearly, while the machine cycle stays roughly the same.

The decision depends on the volume you can actually sell, not on the capacity you can install.

A mould with more cavities than the market needs is idle capital.

Tool Cost Scaling

Cavity cost is not exactly linear: the second cavity costs slightly less than the first, and the fourth less than the third.

Balancing and cavity matching add cost that is not proportional to cavity count.

Ask for the cost per cavity, not the total, so the marginal cost is visible.

Cycle Time

A multi-cavity mould cycles in roughly the same time as a single cavity, because all cavities form simultaneously.

Drying, however, must handle the total output, so a larger mould shifts the constraint to the oven.

This is why adding cavities without drying capacity produces no extra output.

The Volume Calculation

Monthly output = cavities × cycles per hour × hours × yield. Work backwards from the volume to the cavity count.

Include the seasonal peak, since the mould must cover the peak, not the average.

Add a 15 to 20 percent margin for downtime and yield variation.

When Two Moulds Beat One Large Mould

Two smaller moulds allow production to continue during a tool repair or replacement.

They also allow different formats to run in parallel, which matters if the product mix is wide.

The cost difference is often small against the operational flexibility.

When One Large Mould Is Right

A single format at high sustained volume, where the tool cost per unit is the driver.

A plant where press time is the constraint and changeover must be minimised.

A long program where the tool will be amortised fully.

Specification

Write the required monthly output, the peak factor, the yield assumption and the drying capacity available.

Then let the cavity count follow from the arithmetic rather than from a preference.

Review after the first season: actual output against the assumption is the best input for the next mould.

Questions Buyers Ask

How many cavities should an egg carton mould have?

Enough to cover the seasonal peak with a 15 to 20 percent margin, calculated from cycles per hour, hours and yield.

Does a multi-cavity mould take longer to cycle?

Not significantly, since all cavities form at once. The constraint usually shifts to drying capacity.

When is a second mould better than a larger one?

When production continuity matters or the format mix is wide, since two moulds allow repair without stopping and parallel formats.

Why ask for cost per cavity?

Because a total price hides the marginal cost, which falls slightly as cavities are added.

What should be reviewed after the first season?

Actual output against the volume assumption, which is the best input for the next mould decision.

Next Step

Send the volume and the peak factor. You will receive a cavity count calculation with the drying implication, in one reply.

See also egg carton closure tab interference jam line.

See also egg carton mold cavity count capacity planning 2026.

See also egg carton format selection faq.

See also egg carton cold store humidity faq.